1. Technical Field
The present invention relates to a color correction apparatus and method thereof in an image system and, more particularly, to a color correction apparatus and method thereof in an image system capable of automatically processing the color correction by storing reference colorimetric data regarding a predetermined test pattern for estimating the color correction in a storage medium, and then scanning the test pattern so that the color correction can be performed by minimizing an error between the reference data and the scanning data obtained by scanning the test pattern.
2. Related Art
Conventionally, an image system is a system which acquires, processes, outputs, converts, transmits, improves, etc. image signals in compliance with an aim. As examples of the image system, a printer and a scanner are publicly well known and widely used. In addition, a multifunctional machine which integrates the printer and scanner functions, and which performs a document output function is a good example of an image system.
Such multi-functional machines include a scanner which, after radiating and illuminating light having a certain spectrum toward an object such as a document, performs photoelectric conversion which converts optical information reflected from the object into an electrical signal, thereby acquiring image information. A printer is also an essential component part in multi-functional machines, and the recent development of color printers has led to the printing of multicolor images by the use of plural toners or plural ink cartridges. As the supply color printer has increased, high quality or high definition printing has become prevalent in color printing. The color image is obtained through a color resolution process which employs color reproduction characteristics of a color image obtained from a spectral optical system.
As discussed in more detail below, waveforms illustrating the visual characteristic of the human optical system and the spectral characteristic of an image system are important in obtaining color reproduction in modern image systems. Moreover, a color correction process is performed by allowing the visual characteristic of the human optical system to be aligned with or to correspond to the spectral characteristic of the image system. Such a color correction process is typically performed by mathematical operations which are very complicated. As also discussed in more detail below, three methods are employed: a linear transformation method; a polynomial transformation method; and a three-dimensional look-up table method. Of these three methods, certain methods are more accurate than others, and certain other methods are more costly than others. Thus, a particular method must be chosen based on the objective to be achieved, for example, cost or accuracy.
Through a use of a color correction apparatus and method in an image system, color correction is to a certain degree accomplished by correcting the spectrum characteristic of the spectral optical system and the individual variation in light quantity. However, the apparatus and method cannot properly cope with the age-based variation generated by the operating conditions or the environmental differences when performing color correction.
In addition, in an image system, the color image input unit is attached to other image devices having different color reproduction characteristics (such as a monitor, printer or a communication device). Since the color reproduction characteristics of each image device are different, technology capable of performing a device-independent color correction procedure is needed.
Therefore, there is a need for the development of a color correction method and apparatus which adaptively performs color correction according to a spectrum characteristic of a spectral optical system, age-based variation and individual variation in light quantity. That is, there is a need for the development of a color correction method and apparatus which performs color correction without regard to the spectrum characteristic of the spectral optical system, age-based variation, and individual variation in the light quantity.
There is also a need for the development of a color correction method and apparatus which is capable of performing gray level correction prior to performing color correction in order to acquire linearity of gray level characteristics regarding each spectrum of the primary colors (red, green and blue).